The present invention relates to a restraint system for preventing a cylinder of a hydraulic actuator from shifting endwise on or rotating about piston and rod units in the cylinder while permitting the actuator to undergo certain movement as a unit.
U.S. Pat. No. 3,826,295 granted to Johnson et al. on July 30, 1974 discloses a shear head including a main frame supporting a pair of parallel crankshafts which are respectively linked to a pair of cylindrically curved blades for swinging the blades about an axis located equidistant from the crankshafts. Connected between the crankshafts for effecting rotation thereof is a hydraulic actuator having a cylinder in which a pair of pistons and rod units are mounted with the rods projecting oppositely from the cylinder and respectively connected to the crankshafts. Each of the piston and rod units is double acting and fluid is routed to and from the cylinder by a plurality of lines that are connected to the cylinder.
This patented actuator arrangement is not entirely satisfactory since unbalanced forces acting inside the cylinder and line flexure, caused when the shear head is adjusted relative to the boom supporting the same, tend to cause the cylinder to shift lengthwise along and/or rotate about the piston and rod units resulting in damage to the lines connected to the cylinder.